Is 500W enough for 7970 and 5850?

[GoatMonkey]

I have this power supply and a ATi 7970 and my old ATI 5850 running in the same computer. It runs, but I'm worried that I could be overstressing this old power supply. I'm doing some scrypt cryptocoin mining for fun so assume they are both running at full load. This is the power supply:

http://www.newegg.com/Product/Produc...82E16817703015

It's an i7 920 @ 3.2ghz on an evga x58 sli le with 24GB of ram, 3 hard drives. No optical drive.

 

[MustISO]

Recommended minimum for the 7970 is 500W. Personally I would get a high quality unit that is 700W+ for those two cards.

 

[GoatMonkey]

OK, thanks. Good enough for me. Just ordered a nice looking 850W.

 

[Torn Mind]

No. The PSU should be larger than the sum of the TDP of your components.

130W+151W+250W is already 530 W.

 

[nwo]

500W is definitely pushing it.... I tried running a 7950 and 7870 in the same rig on my 500W eVGA and PC shut down a few minutes after being at full (mining) load, even without stressing/loading the CPU.

You have a lot of RAM and a bunch of mechanical drives, which easily exceeds another 50W. I don't even know how you're able to run your system stable, especially since you only have 420W on the 12v rail.

 

[GoatMonkey]

I ordered a new power supply, but I decided to try this out. It has been cranking along for a few hours now. Maybe PC Power & Cooling is delivering more than they say. Of course, while mining the rest of my computer isn't really doing much of anything other than running a web browser. I don't have the intensity maxed out on the miners either. Between the two of them it's getting a little over 1000Kh/s. Not too bad.

 

[nwo]

Between the two of them it's getting a little over 1000Kh/s. Not too bad.

Wow, that's pretty damn good. I barely get over 1000kH/s on my 7970 & 5870.

Yes, some power supplies can handle more load than what they are rated for and they do not put that on the sticker. PC Power & Cooling makes some pretty legit PSUs so I wouldn't be surprised if that's the case.

 

[GoatMonkey]

Well, that was a fun experiment. ~16 hours later the comments on this thread were confirmed. The computer shut down. I removed the old 5850 and everything came back up normally.

 

[nwo]

Well, that was a fun experiment. ~16 hours later the comments on this thread were confirmed. The computer shut down. I removed the old 5850 and everything came back up normally.

You had a good run

Now invest some $$ into a new PSU and cash in on the crypto craze! Or, you can just sell your 5850 for around 100 bucks... What hashrate are you getting on it by the way?

 

[Torn Mind]

PSU efficiency matters for mining rigs, but the initial cost of some highly efficient units can be a huge obstacle to actually getting one. In addition, undervolting and underclocking might need to be employed to further chop down the wattage consumption.

 

[GoatMonkey]

You had a good run

Now invest some $$ into a new PSU and cash in on the crypto craze! Or, you can just sell your 5850 for around 100 bucks... What hashrate are you getting on it by the way?

The 5850 is getting right around 300kh/s. I ordered a Thermaltake 850W that looks like it should be good for these two cards. I'm thinking about putting them in another computer, then upgrading my main with at 1200W and get a couple of 290x cards for it. I also ordered a new case, this nice system is running in an ancient Antec 1080 that I got around 2001. So I'm getting a NZXT 630 case, it looks pretty nice.

EDIT: I was wrong, I looked at my average and it's 280kh/s for the 5850 and the 7970 gets 674kh/s. Close enough, it's a little under 1000 for the pair.

 

[nwo]

I think 280 is a bit low for a 5850. You should aim for about 350. Once you get your new PSU, you can have fun OCing the heck out of it and try to get up there

 

[GoatMonkey]

I think 280 is a bit low for a 5850. You should aim for about 350. Once you get your new PSU, you can have fun OCing the heck out of it and try to get up there

It was bouncing around some, I saw it go over 300 a few times, but the average was 280. I spent some time with different settings on the 7970, it started around 550 at default settings. I'll tweak the 5850 once it's a more permanent setup.

I decided to go all in and have some fun. I also ordered a 1200W Corsair power supply and a pair of R9 290x boards. This is going to get interesting. I'll have 2 machines doing some solid mining.

 

[wowsza]

Well, that was a fun experiment. ~16 hours later the comments on this thread were confirmed. The computer shut down. I removed the old 5850 and everything came back up normally.

you got lucky, i fried my 750w trying to run four 7850's